Eric Knight, the Forestville High School football coach whose star player died of a cocaine overdose earlier this month, had tried hard to teach his young charges the dangers of drug abuse.

His most effective lesson, though, may be the one he never intended to teach: that the pleasure and profit that illicit drugs can provide are not worth the risk.

Knight has been suspended from duty following disclosure of a drug conviction back when he was a 23-year-old student at the University of Maryland. Technically, it wasn't the 1974 conviction for drug possession that led to Knight's being placed on administrative leave by Prince George's County school officials; it was his falsification of an employment application. Asked whether he had ever been convicted of a crime, Knight answered no.

Lying on an application is ground for dismissal.

But while that falsification may have caused him last week's embarrassment, it was allowing himself to be tempted into fooling with drugs that did him in. His troubles would hardly have been less if he had told the truth about his conviction. The Prince George's schools would hardly have risked hiring him to coach young athletes if he had owned up to spending time in jail for conspiracy to possess marijuana. (Other drug-related charges levied against him at the time reportedly were dropped in exchange for his guilty plea.)

The revelation that he lied may wind up costing him his coaching job, but who can say what other professional opportunities he would have lost if he had told the truth? The damage, perhaps permanent, had been done long before Forestville High ever heard of him.

It's a shame too. The school was already in shock at the death of young Rico Marshall, the popular, good-looking and multitalented athlete who died after he allegedly swallowed several crystals of "crack" to avoid arrest.

Forestville's youngsters needed Knight -- not only because he was an outstanding football coach but also because he had built the rapport to help them deal with their loss and also to help them understand what less "cool" adults might have found it impossible to convey: the deadly danger of drug abuse.

This is precisely what he had tried to do in numerous sessions with his athletes. He even held a closed meeting with the school's seniors a few days after Marshall's death, at which he warned the girls that accepting expensive gifts from boys suspected of dealing drugs only encouraged the boys to hustle.

"All that is telling them {is} that it's okay to deal, and Rico died in vain," he told them, according to a report on WUSA-TV.

I don't know if they heard him then, and I don't know if his own troubles make the lesson any clearer now. Teen-agers are notoriously immune to good advice from well-meaning adults and prone to think that, however true the warnings, it can't happen to them.

But even if they see half a hundred drug-linked murders in the metropolitan area so far this year as unrelated to them, a few might react to the deaths of pro-basketball prospect Len Bias and young Rico Marshall and the derailed college careers of two high school athletes charged with drug-related offen-ses. Maybe a few more will react to the jeopardized career of a favored coach.

If drug education is any answer to teen-age drug abuse, area teen-agers should by now have acquired the equivalent of a postgraduate degree.

It may be time now for Prince George's school officials to offer another valuable lesson: forgiveness.

What Eric Knight did -- both his involvement in drugs and his lying about it -- was wrong, and the authorities should leave no doubt on that score.

But what he has done since then -- what he has become since then, according to every account I have heard -- is so right, so valuable, that it would compound tragedy to toss him out of his job now.

There has to be some way -- administrative waiver, gubernatorial pardon or legislative action -- for those responsible for Prince George's children to forgive the wrong that Knight committed and capture the good he can do.

I hope they try to find it. Not just Forestville football players but the youth of the metropolitan area need Eric Knight now more than ever.